• Korean Journal of Materials Research
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• v.26 no.5
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• pp.250-257
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• 2016

Octahedral $Co_3O_4$/carbon nanofiber (CNF) composites are fabricated using electrospinning and hydrothermal methods. Their morphological characteristics, chemical bonding states, and electrochemical properties are used to demonstrate the improved photovoltaic properties of the samples. Octahedral $Co_3O_4$ grown on CNFs is based on metallic Co nanoparticles acting as seeds in the CNFs, which seeds are directly related to the high performance of DSSCs. The octahedral $Co_3O_4$/CNFs composites exhibit high photocurrent density ($12.73mA/m^2$), superb fill factor (62.1 %), and excellent power conversion efficiency (5.61 %) compared to those characteristics of commercial $Co_3O_4$, conventional CNFs, and metallic Co-seed/CNFs. These results can be described as stemmnig from the synergistic effect of the porous and graphitized matrix formed by catalytic graphitization using the metal cobalt catalyst on CNFs, which leads to an increase in the catalytic activity for the reduction of triiodide ions. Therefore, octahedral $Co_3O_4$/CNFs composites can be used as a counter electrode for Pt-free dye-sensitized solar cells.

• Journal of the Korean Institute of Gas
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• v.21 no.4
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• pp.92-102
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• 2017

Fischer-Tropsch synthesis reaction converts syngas (mixture of CO and H2) to valuable hydrocarbon products. Simulation of low temperature Fischer -Tropsch Synthesis reaction and heat transfer at intensified process condition using catalyst filled single and multichannel microchannel reactor is considered. Single channel model simulation indicated potential for process intensification (higher GHSV of $30000hr^{-1}$ in presence of theoretical Cobalt based super-active catalyst) while still achieving CO conversion greater than ~65% and $C_{5+}$ selectivity greater than ~74%. Conjugate heat transfer simulation with multichannel reactor block models considering three different combinations of reactor configuration and coolant type predicted ${\Delta}T_{max}$ equal to 23 K for cross-flow configuration with wall boiling coolant, 15 K for co-current flow configuration with subcooled coolant, and 13 K for co-current flow configuration with wall boiling coolant. In the range of temperature maintained (498 - 521 K), chain growth probability calculated is desirable for low-temperature Fisher-Tropsch Synthesis.

• Journal of Sensor Science and Technology
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• v.9 no.6
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• pp.430-439
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• 2000

$In_2O_3$-based thin film sensor with 500-600 nm thick was fabricated for the detection of CO gas by rf magnetron sputtering. In order to improve both sensitivity to CO gas and selectivity to hydrogen gas containing -CH, ultra-thin transition metal Co catalyst was sputtered over $In_2O_3$ thin film and annealed at $500^{\circ}C$. Sensitivity to CO was maximum at the thickness of Co 2.1 nm and $300^{\circ}C$, and that to $C_3H_8$ was at the thickness of Co 1.4 nm and $350-400^{\circ}C$. From the x-ray photoelectron spectroscopy (XPS) result, ultra-thin Co was existed into CoO covered with $Co_2O_3$ on $In_2O_3$ particles, and thus p-n junction of $In_2O_3(n-type)$-CoO(p-type) was thought to be formed. In this p-n junction type sensors, sensing mechanism with reducing gases can be explained by the variation of depletion layer thickness formed in the interface.